1. Field of the Invention
The present invention relates generally to an auger-type ice making machine and, more particularly, to a novel and improved ice making machine in which a change in the quality of water contained in a refrigerating cylinder for ice formation is electrically detected to thereby cause the water to be discharged from the cylinder in dependence on the result of the detection for the purpose of preventing auger supporting bearings and other parts from being subject to excessive wear.
2. Prior Art
Heretofore, a variety of auger-type ice making mechanisms having various structures have been proposed, as exemplified by those disclosed in Japanese laid-open Utility Model Application Nos. 39,476/1983 and 99,687/1983.
Referring to FIG. 4 of the accompanying drawings showing an ice making machine known heretofore, raw water is supplied to an auger-type ice making mechanism 2 from a water tank 1 which is operated to maintain water at a predetermined level. Ice pieces or pellets as formed by the ice making mechanism are stored in an ice storage chamber 3. When the latter becomes full of the ice pellets, this state is detected by a storage level sensor switch 4, whereby a corresponding detection signal is produced. In response to this signal, a drain valve 5 provided in a drain pipe 8 communicated with the ice making mechanism 2 is opened to thereby allow provably contaminated water within the refrigerating cylinder to be discharged while cleaning the refrigerating cylinder with water supplied from the water tank 1.
Referring to FIG. 5, there is shown another conventional ice making machine, in which the water tank 1 is provided with a water supply pipe incorporating a water supply valve 6 which is opened periodically under the control of a timer independent of the water level detection signal generated by a float switch 7 used for controlling the water level within the water tank 1. By opening the water supply valve 6, the water level within the tank 1 is forced to rise upwardly to thereby cause water within the cylinder of the ice making mechanism 2 to be discharged through a drain pipe 8 under the action of siphonage and replaced by fresh water.
As will be seen, however, each of the prior art ice making machines is so arranged that the water within the refrigerating cylinder is discharged automatically mainly in dependence on a chronographical factor regardless of an actual degree of contamination (or impurity concentration level) of water within the ice making mechanism. Also, in practice, the impurity concentration of water within the refrigerating cylinder is affected by that of the water supplied to the water tank and ice quality (e.g. water content of ice) as manufactured. Nevertheless, in the aforementioned conventional ice making machines, water is discharged from the refrigerating cylinder of the ice making mechanism whenever an ice making operation has been performed over a predetermined period even if the impurity concentration of water is adequately low, i.e. even through there is no need for discharging water from the refrigerating cylinder, which causes significant wasteful consumption of water. Besides, it is to be noted that water within the refrigerating cylinder is usually at a relatively high temperature at the time of starting the ice making operation after a water discharging operation. Consequently, when the water discharge is carried out periodically without consideration of the current water quality, the daily output of the ice making machine will be disadvantageously lowered considerably. On the other hand, the periodical water discharge may also cause such a situation in which the water discharge is not effectuated even when the impurity concentration of water within the refrigerating cylinder has increased excessively after continuation of the ice making operation unless the predetermined discharging time point has been attained. In that case, scales will be deposited on the auger, the refrigerating cylinder, the bearings and other elements of the ice making mechanism, involving degradation in the ice making capability as well as excessive wear in the bearings.